The present invention proposes an alternative to the existing solutions that makes it possible to reduce the on-board weight with equivalent mechanical characteristics.
To this end, an embodiment of the invention is an aircraft strut comprising a primary structure which comprises:                a top stringer,        a bottom stringer,        at least one transverse frame, arranged in a transverse plane, and which links the top stringer to the bottom stringer,        a front end wall, arranged in a transverse plane, and which links a front end of the top stringer to a front end of the bottom stringer,        a rear end wall arranged in a transverse plane, and which links a rear end of the top stringer to a rear end of the bottom stringer.        
According to an embodiment of the invention, the primary structure comprises two lateral frames arranged on either side of the transverse frame, each lateral frame having a lattice form and comprising:                a top beam linked to the top stringer and which extends from the front end wall to the rear end wall,        a bottom beam linked to the bottom stringer and which extends from the front end wall to the rear end wall,        angle ions which link the top beam and the bottom beam.        
This configuration makes it possible, with equivalent mechanical characteristics, to reduce the weight of the primary structure and reduce its manufacturing costs.
According to another feature, the lateral frames are arranged in parallel longitudinal planes.
According to another feature, the top stringer has a profile in the form of an inverted V or U in a vertical longitudinal plane and the bottom stringer has a profile in the form of a V or U in a vertical longitudinal plane, the top beam comprises sections arranged end-to-end which form an inverted V or U identical to the inverted V or U profile of the top stringer and the bottom beam comprises sections arranged end-to-end which form a V or U identical to the V or U profile of the bottom stringer.
According to one configuration, each lateral frame comprises two angle ions arranged in the form of a V, first ends of the two angle ions being linked to the top beam at an area of join of the sections of the top beam, second ends of the two angle ions being linked to the bottom beam at a distance from an area of join of the sections of the bottom beam.
Preferably, each lateral frame comprises at least one end angle ion which links the rear end of the top beam and the rear end of the bottom beam.
According to one embodiment, each top and bottom beam has a section in the form of a T with a head arranged in a vertical longitudinal plane with an internal face oriented towards the interior of the primary structure and a leg at right angles to the head, linked to the internal face of the head and oriented towards the interior of the primary structure.
According to one embodiment, each angle ion has a section in the form of a T with a head arranged in a vertical longitudinal plane, pressed against the internal face of the head of the top and bottom beams and a leg at right angles to the head and oriented towards the interior of the primary structure.
According to another feature, the primary structure comprises a central transverse frame which comprises a top crossmember, a bottom crossmember, two lateral uprights and two eyelets linked to the top crossmember, arranged in vertical longitudinal planes, in the extension of the lateral uprights and each lateral frame comprises at least one eyelet arranged in a vertical longitudinal plane and linked to the top beam, each eyelet being substantially identical to the eyelets of the central transverse frame and offset towards the exterior of the primary structure relative to the eyelets.
Another subject of the invention is an aircraft comprising at least one strut according to the invention.